Apparatus for freezing a liquid



May 4, 1965 Filed Jan. 9, 1963 E. WILBUSHEWICH APPARATUS FOR FREEZING A LIQUID 2 Sheets-Sheet l May 4, 1965 Filed Jan. 9, 1963 E. WILBUSHEWICH APPARATUS FOR FREEZING A LIQUID 2 Sheets-Sheet 2 /A/l/EA/Toe gym GEN 7 United States Patent Oce APPARATUS EUR A LQUHD Eugen Wilbushewich, loteistrasse 6l, Postfach,

Zurich 23, Switzerland Filed Jian. 9, 1963, Ser. No. 250,325 Claims priority, application Switzerland, Feb. 7, 1962., 1,489/62 '7 Claims. (Ci. o2-352) The present invention relates to improvements in the type of freezing apparatus wherein a liquid is frozen in a mold which has an internal evaporator extending into the mold from one end and a jacket evaporator. More particularly, this invention is concerned with an improved refrigeration circuit for circulating refrigerant through the evaporators and also with an improved support structure for the internal evaporator.

Conventional freezing plants of this general type include a liquid separator including a sump, a feed line connected to the separator for supplying liquefied refrigerant from a condenser to the sump, a suction line connected to the separator for delivering evaporated refrigerant therefrom to a compressor, the output of the compressor leading to the condenser, and a receiver vessel to which liquefied refrigerant may be drained from, or supplied to, the evaporators.

lt is one of the objects of the invention to provide a refrigeration circuit with a reduced number of lines interconnecting the evaporators, the liquid separator and the receiver vessel.

it is another object to replace the conventional gravity feed` of liquefied refrigerant from the liquid separator to the mold by a positive feed means, such as a pump, whereby it becomes unnecessary to place the separator above the mold and the level of the separator is independent of the level of the mold. The result of accomplishing these objects is a considerable simplification of the apparatus and a reduction in its space requirements which may be of importance in all plants where space is at a premium, for instance aboard ships.

lt is another object of the present invention to provide a simplified mounting for the internal evaporator, which makes-dismantling of the molds easy.

lt is a further object of this invention to provide an evaporator structure and interconnection between jacket and internal evaporators in each mold, which facilitates the refrigerant circulation therethrough.

The above and other objects of the invention are accomplished with a refrigeration circuit which includes a main liquefied refrigerant feed line leading from the separator sump to one of the evaporators, a main evaporated refrigerant return line leading from the other one of the evaporators to the liquid separator, the liquefied refrigerant thus entering one of the evaporators through the main feed line and evaporated refrigerant leaving the other evaporator through the main return line, whereby the evaporators are connected in the circuit in series, a main hot gaseous refrigerant feed line leading to one of the evaporators and another main line leading from one of the evaporators to the liquid receiver vessel for transferring liquefied refrigerant displaced by the hot gaseous refrigerant from the evaporators to the receiver vessel and for transferring liquefied refrigerant from the receiver vessel to the one evaporator. Control means, such as a rotary valve, is arranged for controlling the respective flow of the refrigerant between each one of the circuit main lines andthe evaporators and a feed pump has an intake connected to the separator sump and an output to the main liquefied refrigerant feed line.

Preferably, a first connecting line has one end connected to the jacket evaporator and has two branches at the other end, a third connecting line has one end connected to lgld@ Fatented May d, 1%65 to the internal evaporator and has two branches at the other end, a third connecting lie has one end connected to the main hot gaseous refrigerant line, a fourth connecting line has one end connected to the other main line and has two branches at the other end, a fifth connecting line has one end connected to the main evaporated refrigerant return line and a sixth connecting line has one end connected to the main liquefied refrigerant feed line. The control valve means is mounted between the other ends of the connecting lines and the main lines and is movable into the following four positions:

(l) A first or freezing stage wherein it simultaneously establishes Comunication between the sixth connecting line and one of the branches of the first connecting line, and the fifth connecting line and one of the branches of the second connecting line while interrupting communication between the third connecting line and the other branch of the second connecting line, and the other branch of the rst connecting line and one of the branches of the fourth connecting line.

(2) A second or defrosting stage wherein it simultaneously establishes communication between the third connecting line and the other branch of the second connecting line, and the one branch of the first connecting line and the one branch of the fourth connecting line while interrupting communication between the fifth connecting line and the one branch of the second connecting line, and the one branch of the first connecting line and the sixth connecting line.

(3) A third or pre-freezing stage wherein it simultaneously establishes communication between the one branch of the second connecting line and the sixth connecting line, and the other branch of the first connecting line and the other branch of the fourth connecting line while interupting communication between the third connecting line and the other branch of the second connecting line and the one branch of the first connecting line and the sixth connecting line.

(4) A fourth or idle stage wherein it interrupts communication between all the connecting and main lines.

The internal evaporator consists of an outer tube sealed at the bottom and having an open end and an inner tube coaxially and concentrically mounted therein. The inner tube has two open ends and the tubes define an annular evaporator space.

According to one embodiment of the invention, conduit means is provided between the jacket evaporator and the annular evaporator space of the internal evaporator, and the inner tube is in communication with the second connecting line.

According to another embodiment, conduit means is provided between the jacket evaporator and the internal evaporator inner tube, and the annular evaporator space of the internal evaporator is in communication with the second connecting line.

The above and other objects, advantages and features of the present invention will become more apparent in the following detailed description of certain now preferred embodiments, taken in conjunction with the accompanying drawing wherein PEG. l is a diagrammatic view of a refrigeration plant according to this invention; and

FGS. 2 and 3 are vertical cross sections of an alternate embodiment of the ice rnold used in the plant, shown in the freezing and defrosting position, respectively.

Referring now to the drawing and first to FIG. l, there are shown four batteries Bl, B2, B3 and B4 of ice molds, each battery bein" represented by a single freezing mold. Suitable refrigeration equipment, including a compressor and a condenser, is provided to supply liquid refrigerant and hot gaseous refrigerant to the ice mold batteries during the freezing and defrosting cycles, respectively, as is well known in such refrigeration plants and illustrated, for instance, in my U.S. Patent No. 2,967,402, of January 10, 1961. To simplify the drawing and clearly direct it only to the improvements provided by the present invention, this refrigeration equipment and other conventional refrigeration plant means have not been shown.

The ice molds shown in FIG. l comprise external mold walls 3 defining a freezing chamber 1 of rectangular cross section. For instance, the freezing chambers may be 2S cm. wide and 56 cm. long. Outer walls 4 surround the mold walls 3 to form a jacket evaporator 5 about each ice mold. To expedite freezing, a plurality of internal evaporators extend into the freezing, a plurality of internal evaporators extend into the freezing chamber of each ice mold, two such internal evaporators being shown.

Each internal evaporator consists of two coaxially and concentrically mounted tubes 2 and 6, the outer tubes 2 being sealed at their bottoms. The freezing chamber 1 is covered by closure member 8 and a top cover 12 defines a chamber with the closure member, which is separated into an upper compartment 11 and lower compartment 7 by separating wall 9. The annular evaporator space between tubes 2 and 6 is in communication with the lower compartment '7 which, in turn, communicates with the jacket evaporator through conduits 10. The inner tubes 6 are in communication with upper compartment 11.

At its bottom, the freezing chamber 1 is closed by any suitable movable cover which will open under the pressure of the expanding frozen liquid in the freezing chamber, as is well known in this type of refrigeration plant. kUseful pivotal fiaps for this purpose have been shown, for instance, in my above-mentioned U.S. Patent No. 2,967,402 and, to leave the drawing unencumbered by conventional structures, this has not been illustrated.

The present invention is more particularly concerned with improvements in the supply circuit for the liquid refrigerant and the hot gaseous defrosting medium, which will now be described in detail.

Liquefied refrigerant is fed to the refrigeration plant from a condenser and pressure reducing valve (not shown) through refrigerant feed line 13. Hot gaseous refrigerant is delivered to the ice molds during the defrosting cycle from the discharge side of the compressor (not shown) throughy feed line 14. Evaporated refrigerant is sucked into the compressor from liquid separator 19 through suction line 15. The compressed refrigerant is delivered to the condenser and the cold liquefied refrigerant is fed from the condenser to the ice molds in a Inanner well known per se.

An auxiliary line 16 connects the evaporators of all the ice molds to closed receiver vessel 17 and, in a manner to be described hereinafter, drains refrigerant from, or supplies to, the evaporators.

The liquid separator has a sump 18 for liquid and an upper chamber 20 for evaporated refrigerant, another common main line 21 being Vconnected to the evaporators of all the ice moldsfor feeding evaporated refrigerant from the evaporators to the chamber 20 of separator 19. Liquefied refrigerant is fed into the sump 1S through feed line 13. Evaporated refrigerant is removed from upper chamber 20 through suction pipe 15. Furthermore, supply conduit 22 leads from the liquid receiver vessel 17 to the upper chamber 20 of the liquid separator 19. Outlet conduit 7.9 leads from sump 18 to feed pump 30 which delivers liquid refrigerant to all the evaporators of the ice molds through a third main line 32 connected to all the molds. v

Supply conduit 22 ends in two branch lines, line 25 leading to the top 0f receiver vessel 17 while branch line 26 leads to its bottom. An overflow line 25 connects the branch lines with the main portion of conduit 22. A float valve 23 is arranged in the conduit Z2 and a by-pass line connects the overflow line 24 with a portion of the conduit 22 ahead of the fioat valve, the by-pass line being normally closed by valve 27.

In this arrangement, when the level of liquid refrigerant in vessel 17 rises to that of overflow line 24, the liquid refrigerant passes through lines 26, 24 and conduit 22 into the upper chamber of the liquid separator 19. However, the pressure in the receiver vessel 17 may exceed that in separator 19 without refrigerant passing from one into the other because this excess pressure will close the float valve 23, thus preventing communication between the receiver vessel and the separator as long as valve 27 also is closed.

The supply of liquid refrigerant from sump 18 of the separator to the feed pump 3) is controlled by valve 28 and another valve 31 controls the delivery of refrigerant from the pump to the main 32.

The main liquid refrigerant feed line 32, the hot gaseous refrigerant feed line 14, the main evaporated refrigerant return line 21 and the common main line 16 to the liquid receiver are connected to the evaporators of each ice mold of all the batteries by the following identical valve means;

Each battery of ice molds has associated therewith a rotary slide valve having four separate channels 34, 35, 36 and 37. Depending on the angular position of each valve, different ones of the feed and return lines are connected or diseonected from the evaporators of the respective battery and four successive operating cycles are indicated diagrammatically in FIG. 1 in connection with adjaeentbatteries, the valve being turned by in each successive battery.

1n the valve position illustrated in connection with battery B1, the main liquid refrigerant feed line 32 is connected, and supplies liquefied refrigerant, to the jacket evaporators S of the ice molds by way of connecting line 33 leading from line 32 through valve channel 35 into one branch of manifold 39, the manifold leading to distributing line 40 whence individual connecting lines 41 deliver the liquefied refrigerant into the evaporator jackets 5 of each ice mold of the battery. The partly evaporated refrigerant then moves from the evaporator jacket through conduit 19 and chamber 7 into the annular evaporating space of the inner` evaporators.

In this valve position, evaporated refrigerant, which rises through the inner concentric tube 6 into the upper compartment 11, leaves the ice molds and is returned through distributing line 45 and connecting line 44 through valve channel 36 and connecting line 46 to main evaporated refrigerant return line 21 to the liquid separator 19.

During this freezing cycle of battery B1, the hot gaseous refrigerant feed line 14 and the common main line 16 are disconnected from the ice molds.

During the defrosting cycle shown in the valve position of battery B2, the hot gaseous refrigerant feed line 14 is connected through connecting line 43 and valve channel 37 with one of the branches of a manifold leading to connecting line 44 which delivers the hot gas through distributing line 45'into the upper compartment 11 whence it passes through the inner tube 6, the annular space of the inner evaporators, lower compartment 7 and, through conduit 1t) into the jacket evaporator 5. It leaves the jacket evaporator through connecting lines 41 and passes into distributing line 40 whence it flows into manifold 39 and, through one of its branches and valve channel 35, into one of the branches of manifold 42 which delivers the hot gas to common main line 16 and into the liquid receiver 17. Meanwhile, the evaporated refrigerant return line 21 and the liquefied refrigerant feed line 32 are disconnected from the ice molds.

In the pre-freezing cycle of battery B3, liquefied refrigerant is supplied yfrom the liquid receiver 17 through common main line 16 and one of the branches of the manifold connecting line 42, through valve channel 34 into one of the 'branches of manifold 39 whence it flows into the evaporators in the manner indicated hereinabove in connection with battery B1. At the `same time, evaporated refrigerant is returned through connecting line le through valve channel 36 into return line 21, also in the manner described in connection with battery B1. Meanwhile, gaseous refrigerant feed line 1d and liquefied refrigerant feed line 32 are disconnected from the ice molds.

rIn the idle position of battery Bd, all conections to the ice molds are interrupted.

The above-described apparatus operates as follows:

To initiate a freezing cycle (battery Bl), the freezing chambers 1 of all the ice molds of the battery are closed at the bottom by movable bottom closure member (not shown), a liquid to be frozen, such as water, is placed in the freezing chambers of the molds and the valve means is turned to the posi-tion shown at battery B1. in this position and with the valve Si open, feed pump will delivery liquefied refrigerant into the evaporators of the ice molds in the above-indicated manner. The refrigerant almost completely evaporates within the evaporators and the refrigerant vapor is returned through line 2f to liquid separator 19, as described hereinabove.V The vapor is there separated into a liquid component, which settles in sump f8, and a dry Vapor component, which is fed to the compressor (not shown) by suction line 1S. The evaporating refrigerant in the evaporators extracts sufficien-t heat from the liquid in the freezing chamber 1 to freeze the liquid and turn it into a block of ice. The movable bottom closure (not shown), which had become frozen to the mold walls during the freezing cycle, is eventually pressed away from the mold Walls by the expanding -ice in the freezing chamber in a conventional manner descri-bed, for instance, in my aforementioned US. patent.

When the liquid has become solidly frozen to form an ice block, the rotary Valve is turned into the defrosting position shown in association with battery B2. The valve may, of course, be turned manually or it may be automatically controlled inV any desired timed cycle. N ow, as hereinabove described, thel compressor will discharge hot gaseous refrigerant through feed line 14 into the evaporators, thus defrosting the ice block from the evaporator walls so that it may be harves ed by gravity through the open bottom of the freezing space. Liqueed refrigerant remaining in the jacket evaporators of the molds will be pushed ahead by the hot gaseous refrigerant and pass through manifold 39 into manifold whence it will fiow into the liquid receiver' vessel 17.

As long as the liquid refrigerant does not rise inside vessel 7 to the level of overiiow line 2d, the pressure in the vessel keeps the float valve 23 closed and the refrigerant vapor in the vessel becomes increasingly more compressed, upwardly displaced refrigerant vapor returning to the bottom of the vessel 17 through branch lines 25, 2d. When the liquid level rises to that of overflow line 2d, liquid will drip into iioat valve Z3, raising its liquid level and thus opening the valve. Surplus refrigerant `will now flow from the receiver vessel 17 through line 22 into the liquid separator 19, where it will be combined with the liquid refrigerant delivered from the condenser through feed line 13.

In the short pre-freezing stage shown in association with battery B3, liquid refrigerant from vessel '17 is returned to the evaporators in the above-indicated manner, the refrigerant having been received from the defrosting cycle of another battery of the plant just described. This will cause the mold walls to be cooled down again, progressively from bottom to top, permitting the tight sealing of the freezing chambers ll of each mold by freezing the movable closure member (not shown) to the bottom of the mold walls. The closed freezing chambers are then again filled with a liquid to be frozen and the freezing cycle may be initiated again.

In a multi-'battery installation, it will be advantageous to operate the batteries in suitable timed sequence, such as illustrated in FIG. 1. Experience has shown that water may be frozen into ice blocks of about 150 kg. weight in about 1%. hours. A few minutes are required for defrosting and Ian even shorter period of time for returning liquefied refrigerant into the evaporators so as to enable the bottom closure members to be frozen to the bottoms 4of the molds.

In most respects, the modified ice mold shown in FIGS. 2 and 3 is similar to the molds shown in FIG. 1 and to avoid a repetition of the description, like structural parts functioning in a like manner have been indicated by the same reference numerals in both embodiments. The only differences are in the arrangement of the connecting conyduit between the jacket evaporator 5 and the upper cornpartment Till, as well as in the connection of the evaporators to distributing line 45. As shown, conduit means Sti constitutes a communication between the jacket evaporator and the upper compartment 141', and the distributing line 45 is connected to the lower compartment '7 by means of connecting line 51. The operation of this ernbodiment of the ice mold in the refrigeration plant of FIG. l will be quite similar as hereinabove described, deviating only in the following aspects:

During the frezing cycle (FIG. 2, rotary valve position as in battery B1), the liquid refrigerant pumped into the main feed line 32 will enter at the bottom of jacket evaporator S and rise therein, while partially evaporating, as in the embodiment of FG. 1. However, it will now pass through conduit means 5@ into the upper compartment 11 whence i-t will iiow through inner tubes d dowi wardly and the annular evaporator space of the inner evaporators upwardly into lower compartment 7. The rather fully evaporated refrigerant will then leave the ice mold through connecting line Si and flow through distributing line 45 and connecting line de into return line 2f, as in the embodiment of FIG. 1.

In the defrostin-g stage (FG. 3 and rotary valve position as in battery B2), the hot gaseous refrigerant flows into the ice mold through connecting line 44, distributing line 45 and each connecting line 51 whence it passes through lower compartment 7, the annular evaporator spaces of the inner evaporators, the inner tubes 6, the Vup per compartment 11 and the conduit means 50 into the jacket evaporator 5 Wherefrom it is removed at the bottom by connecting line 41 and drained into receiver vessel 17.

In the liquid return position of the rotary valve, for a short period only, line lil is again connected with receiver vessel 17 and with lines 51, d4 to communicate with the return line for liquid-laden refrigerator vapors. Then, liquid refrigerant from the receiver vessel and from the evaporators of another battery which happens to be in the defrosting stage will return via line 41 into the jacket evaporators S, displacing any refrigerant contained herein in the form of a mixture of gaseous and condensed liquid, which has been developed by heat exchange during defrosting, and passing the displaced liquid via lines 51, 45, 44 to the liquid separator 19.

The ice mold of FIGS. 2 and 3 has certain advantages over that of FIG. 1. In the first place, the evaporating refrigerant will pass upwardly through all evaporator spaces during the freezing cycle. This will enable any developing bubbles to rise freely and without hindrance from counter-currently flowing refrigerant, thus improving the refrigerant circulation and obtaining a better heat exchange between the refrigerant and the liquid to be frozen. Secondly, it is advantageous for the refrigerant circulation that mainly liquid refrigerant is fed through the thin tubes 6, rather than mostly evaporated refrigerant which, due to evaporation, has been greatly ein panded in volume.

Equally, it is advantageous during the defrosting cycle to havethe hot gaseous refrigerant come into contact immediately with the walls of the inner evaporators so i? that the frozen blocks adhering thereto becomes detached more rapidly.

As will be appreciated from the above description, in all embodiments of the refrigeration plant of this invention, the jacket evaporators of all ice molds of each battery are connected to the plant by a single line 40, 39 and the inner evaporators of all ice molds of each battery are also connected to the plant by a single line 45, 44. The refrigeration equipment, including the compressor, the condenser, the liquid separator 19, the feed pump 30 and the liquid receiver vessel 17, is connected to all the batteries of the installation by only four main lines, i.e. main liquid refrigerant feed line 32, hot gaseous refrigerant feed line 14, main evaporated refrigerant return line Z1 and common main line 16 leading to the receiver vessel. Also, the separator 19 may be arranged at any level in relation to the batteries because the pressure needed to fill the evaporators with liquid refrigerant is supplied by feed pump 30 and not by the static pressure of the liquid in the separator.

Also, each rotary slide valve leads only to six lines of which lines 33, 43 and 46 lead directly to respective ones of the main lines while manifolds 39 and 44 lead to the evaporators and manifold 42 leads to the fourth main line. Thus, the number of lines in the refrigerating circuit is considerably reduced in comparison to the circuit system of my above-mentioned U.S. Patent No. 2,967,402, for instance,

Also, the conduit structure interconnecting the jacket evaporator of the ice mold with the internal evaporators via conduit means 1G or 50 and compartments 7 and 11 facilitates the ready fiow of refrigerant into and out of the evaporators while constituting a particularly simple construction making easy dismantling of the top of the ice molds and the internal evaporators connected thereto, or integral therewith, possible.

Because of the reduction in the number of refrigerant circuit lines, the simplification of the control valve determining the flow of refrigerant from the main lines to the evaporators, and the possibility of placing the liquid separator at any desired level, less space is required for the refrigeration plant. Also, dismantling of the ice molds has been simplified by the special construction of the mold tops and the internal evaporators connected thereto.

With the described arrangement of afeed pump delivering refrigerant to the evaporators, it has become possible to freeze about 40% more liquid than was possible with the same ice molds receiving the liquid refrigerant from a gravity-controlled feed circuit. Also, it has been found that freezing losses are considerably reduced so that the power consumed per ton of ice or other frozen product is lower.

While the invention has been specifically described in connection with certain'now preferred embodiments, it will be clearly understood that many modifications and variations may occur to the skilled in the art, particularly after benefiting from the present teaching, without departing from the spirit and scope of this invention, as defined in the appended claims.

What I claim is:

1. In an apparatus for freezing a liquid, comprising (a) a mold including (l)- a jacket evaporator defining a freezing chamber and (2) an internal evaporator extending into the freezing chamber;

(b) a liquid separator including a sump;

(c) a feed line connected to the separator for supplying liquefied refrigerant to the sump;

(d) a liquid receiver vessel;

(e) a refrigeration circuit for circulating refrigerant through the evaporators, said circuit including (3) a main liquified refrigerant feed line leading fromA the liquid separator sump to the jacket evaporator,

(4) a main evaporated refrigerant return line leading from the internal evaporator to the liquid separator, the liquefied refrigerant being capable of entering said jacket evaporator through the main feed line and evaporated refrigerant being capable of leaving the internal evaporator through the main return line, whereby the evaporators are connected in the circuit in series,

(5) a main hot gaseous refrigerant feed line leading to one of said evaporators, and

(6) an auxiliary main line leading from the latter one of said evaporators to said liquid receiver vessel for transferring liquefied refrigerant dis placed by the hot gaseous refrigerant from the evaporators to the receiver vessel and for transferring liquefied refrigerant from the receiver vessel to said one evaporator;

(f) control means for controlling the respective ow of the refrigerant between each one of said circuit main lines and the evaporators; and

(g) a feed pump forming part of said main liquefied refrigerant feed line, said pump having an intake connected to said separator sump.

2. The apparatus of claim 1, further comprising a first connecting line between said control means and said jacket evaporator and a second connecting line between said control means and said internal evaporator, said control means establishing communication between the main liquefied `refrigerant feed line and the first connecting line, and the main evaporated refrigerant return line and the second connecting line while simultaneously interrupting communication to the main hot gaseous refrigerant feed line and the said auxiliary main line.

3. The apparatus of claim 2, further comprising a third connecting line between said control means and said main hot gaseous refrigerant feed line and a fourth connecting line between said control means and said auxiliary main line, said control means establishing communication between the main hot gaseous refrigerant feed line and the second connecting line, and the auxiliary main line and the rst connecting line while simultaneously interrupting communication to the main liquefied refrigerant feed line and the main return line.

4. The apparatus of claim 3, wherein said control means is a multiple channel -rotary valve mounted between said connecting lines and said main lines.

5. The apparatus of claim 3, wherein said internal evaporator consists of an outer tube sealed at the bottom and having an open end, and an inner tube coaxially and concentrically mounted therein, the inner tube having two open ends and the tubes defining an annular evaporation space, conduit means is provided between the jacket evaporator and the annular evaporator space of the inter-nal evaporator, and the inner tube is in communication with the second connecting line.

6. The apparatus of claim 3, wherein said internal evaporator consists of an outer tube sealed at the bottom and having an open end, and an inner tube coaxially a-nd concentrically mounted therein, the inner tube having two open ends and the tubes defining an annular evaporation space, conduit means is provided between the jacket evaporator a-nd the internal evaporator inner tube, and the annular evaporator space of the internal evaporator is in communication with the second connecting line.

7. In an apparatus for freezing a liquid, comprising (a) a mold including (l) a jacket evaporator defining a freezing chamber and (2) an internal evaporator extending into the freezing chamber;

(b) a liquid separator including a sump;

(c) a feed line connected to the separator for supplying liquefied refrigerant to the sump;

(d) a liquid receiver vessel;

(e) a refrigeration circuit for circulating refrigerant through the evaporators, said circuit including (3) a main liquefied refrigerant feed line leading from the liquid separator sump to the jacket evaporator,

(4) a main evaporated refrigerant return line leading from the internal evaporator to the liquid separator, the liquefied refrigerant being capable of entering said jacket evaporator through the main feed line and evaporated refrigerant being capable of leaving the internal evaporator through the main return line, whereby the evaporators are connected in the circuit in series,

(5) a main hot gaseous refrigerant feed line leading to one of said evaporators, and

(6) an auxiliary main line leading from the latter one of said evaporators to said liquid receiver vessel for transferring liquefied refrigerant displaced by the hot gaseous refrigerant from the evaporators to the receiver vessel and for transferring liquefied refrigerant from the receiver vessel to said one evaporator;

(7) a first connecting line having one end connected to said jacket evaporator and having two branches at the other end respectively connected to said main liquefied refrigerant feed line and said auxiliary main line,

(8) a second connecting line having one end connected to said internal evaporator and having two branches at the other end respectively connected to said main evaporated refrigerant return line and said main hot gaseous refrigerant feed line,

(9) a third connecting line having one end connected to said main hot gaseous refrigerant line and another end connected to one of the branches at the other end of the second connecting line,

(l0) a fourth connecting line having one end connected to said auxiliary main line and having two branches at the other end connected to the branches at the other end of the rst connecting line,

(11) a fifth connecting line having one end connected to the said main evaporated refrigerant return line and another end connected to the other one of the branches at the other end of the second connecting line, and

(12) a sixth connecting line having one end connected to the main liquefied refrigerant feed l@ line and another end selectively connected to one of the branches at the other ends of the first and fourth connecting lines,

(f) control valve means mounted between the other ends of the connecting lines and said main lines for controlling the respective flow of the refrigerant between each one of said circuit main lines and the evaporators, said control means in a rst position simultaneously establishing communication between the sixth connecting li-ne and one of the branches of the first connecting line, and the fifth connecting line and one of the branches of the second connecting line while interrupting communication between the third connecting line .and the other one of the branches of the second connecting line, and the other one of the branches of the first connecting line a-nd one of the branches of the fourth connecting line, said control means in a second position simultaneously establishing communication between the third connecting line and the other one of the branches of the second connecting line, and the one branch of the first connecting line and the one branch of the fourth connecting line while interrupting communication between the fth connecting line and the one branch of the second-connecting line, and the one branch of the first connecting line and the sixth connecting line, said control means in a third position simultaneously establishing communication between the one branch of the second connecting line and the sixth connecting line, and the other one of the branches of the first connecting line and the other one of the branches of the fourth connecting line while interrupting communication between the third connecting line and the other branch of the second connecting line, and the one branch of the rst connecting line and the sixth connecting line, and said control means finally interrupting communication between all the connecting and main lines in a fourth position; and

(g) a feed pump forming part of said main liquied refrigerant feed line, said pump having an intake connected to said separator sump;

References Cited by the Examiner UNITED STATES PATENTS 2,967,402 1/ 61 Wilbushewich 62-352 X 2,997,861 8/ 61 Kocher et al 62-352 X ROBERT A. OLEARY, Primary Examiner. 

1. IN AN APPARATUS FOR FREEZING A LIQUID, COMPRISING (A) A MOLD INCLUDING (1) A JACKET EVAPORATOR DEFINING A FREEZING INTO THE BER AND (2) AN INTERNAL EVAPORATOR EXTENDING INTO THE FREEZING CHAMBER; (B) A LIQUID SEPARATOR INCLUDING ASUMP; (C) A FEED LINE CONNECTED TO THE SEPARATOR FOR SUPPLYING LIQUEFIED REFRIGERANT TO THE SUMP; (D) A LIQUID RECEIVER VESSEL; (E) A REFRIGERATION CIRCUIT FOR CIRCULATING REFRIGERANT THROUGH THE EVAPORATORS, SAID CIRCUIT INCLUDING (3) A MAIN LIQUIFIED REFRIGERANT FEED LINE LEADING FROM THE LIQUID SEPARATOR SUMP TO THE JACKET EVAPORATOR, (4) A MAIN EVAPORATED REFRIGERANT RETURN LINE LEADING FROM THE INTERNAL EVAPORATOR TO THE LIQUID SEPARATOR, THE LIQUEFIED REFRIGERANT BEING CAPABLE OF ENTERING SAID JACKET EVAPORATOR THROUGH THE MAIN FEED LINE AND EVAPORATED REFRIGERANT BEING CAPABLE OF LEAVING THE INTERNAL EVAPORATOR THROGH THE MAIN RETURN LINE, WHEREBY THE EVAPORATORS ARE CONNECTED IN THE CIRCUIT IN SERIES, (5) A MAIN HOT GASEOUS REFRIGERANT FEED LINE LEADING TO ONE OF SAID EVAPORATORS, AND (6) AN AUXILIARY MAIN LINE LEADING FROM THE LATTER ONE OF SAID EVAPORATORS TO SAID LIQUID RECEIVER VESSEL FOR TRANSFERRING LIQUEFIED REFRIGERANT DISPLACED BY THE HOT GASEOUS REFRIGERANT FROM THE EVAPORATORS TO THE RECEIVER VESSEL AND FOR TRANSFERRING LIQUEFIED REFRIGERANT FROM THE RECEIVER VESSEL TO SAID ONE EVAPORATOR; (F) CONTROL MEANS FOR CONTROLLING THE RESPECTIVE FLOW OF THE REFRIGERANT BETWEEN EACH ONE OF SAID CIRCUIT MAIN LINES AND THE EVAPORATORS; AND (G) A FEED PUMP FORMING PART OF SAID MAIN LIQUEFIED REFRIGERANT FEED LINE, SAID PUMP HAVING AN INTAKE CONNECTED TO SAID SEPARATOR SUMP. 